// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef UI_GFX_WIN_WINDOW_IMPL_H_
#define UI_GFX_WIN_WINDOW_IMPL_H_

#include <string>

#include "base/logging.h"
#include "base/macros.h"
#include "ui/gfx/geometry/rect.h"
#include "ui/gfx/gfx_export.h"
#include "ui/gfx/native_widget_types.h"
#include "ui/gfx/win/msg_util.h"

namespace gfx {

// An interface implemented by classes that use message maps.
// ProcessWindowMessage is implemented by the BEGIN_MESSAGE_MAP_EX macro.
class MessageMapInterface {
public:
    // Processes one message from the window's message queue.
    virtual BOOL ProcessWindowMessage(HWND window,
        UINT message,
        WPARAM w_param,
        LPARAM l_param,
        LRESULT& result,
        DWORD msg_map_id = 0)
        = 0;
};

///////////////////////////////////////////////////////////////////////////////
//
// WindowImpl
//  A convenience class that encapsulates the details of creating and
//  destroying a HWND.  This class also hosts the windows procedure used by all
//  Windows.
//
///////////////////////////////////////////////////////////////////////////////
class GFX_EXPORT WindowImpl : public MessageMapInterface {
public:
    WindowImpl();
    virtual ~WindowImpl();

    // Causes all generated windows classes to be unregistered at exit.
    // This can cause result in errors for tests that don't destroy all instances
    // of windows, but is necessary if the tests unload the classes WndProc.
    static void UnregisterClassesAtExit();

    // Initializes the Window with a parent and an initial desired size.
    void Init(HWND parent, const gfx::Rect& bounds);

    // Returns the default window icon to use for windows of this type.
    virtual HICON GetDefaultWindowIcon() const;
    virtual HICON GetSmallWindowIcon() const;

    // Returns the HWND associated with this Window.
    HWND hwnd() const { return hwnd_; }

    // Sets the window styles. This is ONLY used when the window is created.
    // In other words, if you invoke this after invoking Init, nothing happens.
    void set_window_style(DWORD style) { window_style_ = style; }
    DWORD window_style() const { return window_style_; }

    // Sets the extended window styles. See comment about |set_window_style|.
    void set_window_ex_style(DWORD style) { window_ex_style_ = style; }
    DWORD window_ex_style() const { return window_ex_style_; }

    // Sets the class style to use. The default is CS_DBLCLKS.
    void set_initial_class_style(UINT class_style)
    {
        // We dynamically generate the class name, so don't register it globally!
        DCHECK_EQ((class_style & CS_GLOBALCLASS), 0u);
        class_style_ = class_style;
    }
    UINT initial_class_style() const { return class_style_; }

protected:
    // Handles the WndProc callback for this object.
    virtual LRESULT OnWndProc(UINT message, WPARAM w_param, LPARAM l_param);

    // Subclasses must call this method from their destructors to ensure that
    // this object is properly disassociated from the HWND during destruction,
    // otherwise it's possible this object may still exist while a subclass is
    // destroyed.
    void ClearUserData();

private:
    friend class ClassRegistrar;

    // The window procedure used by all Windows.
    static LRESULT CALLBACK WndProc(HWND window,
        UINT message,
        WPARAM w_param,
        LPARAM l_param);

    // Gets the window class atom to use when creating the corresponding HWND.
    // If necessary, this registers the window class.
    ATOM GetWindowClassAtom();

    // All classes registered by WindowImpl start with this name.
    static const wchar_t* const kBaseClassName;

    // Window Styles used when creating the window.
    DWORD window_style_;

    // Window Extended Styles used when creating the window.
    DWORD window_ex_style_;

    // Style of the class to use.
    UINT class_style_;

    // Our hwnd.
    HWND hwnd_;

    // For debugging.
    // TODO(sky): nuke this when get crash data.
    bool got_create_;
    bool got_valid_hwnd_;
    bool* destroyed_;

    DISALLOW_COPY_AND_ASSIGN(WindowImpl);
};

} // namespace gfx

#endif // UI_GFX_WIN_WINDOW_IMPL_H_
